This section provides background information related to the present disclosure, which is not necessarily prior art.
Prior art FIG. 1 illustrates a blower assembly 10, which includes a housing 12 with a blower wheel 14 therein. The blower wheel 14 includes a plurality of blower blades 16. The blower wheel 14 rotates about a center axis 18. As the blower wheel 14 rotates, the blower blades 16 generate airflow through the housing 12 to a discharge outlet 20. From the discharge outlet 20 airflow generated by the blower wheel 14 can be directed to an evaporator 22, or to any other suitable device and/or location. As the blower wheel 14 rotates in the clockwise direction, some of the airflow generated may follow the blower wheel 14 and recirculate by continuing to circulate with the blower wheel 14 instead of flowing to the discharge outlet 20.
To divert airflow from recirculating with the blower wheel 14, a cut-off resonator 30 can be included within the housing 12 adjacent to the blower wheel 14. The cut-off 30 effectively peels airflow off of the blower wheel 14, and thereby increases the volume of airflow flowing to and through the discharge outlet 20. In the example of FIG. 1, the cut-off 30 is a straight cutoff, and includes an upstream surface 32 generally facing the blower wheel 14. A downstream surface 34 is opposite to the upstream surface 32, and an upper edge 36 is between the upstream surface 32 and the downstream surface 34. The cut-off 30 can be made of any suitable material, such as any suitable polypropylene, acrylonitrile butadiene styrene (ABS), or any other suitable plastic material. The cut-off 30 can be secured within the housing 12 in any suitable manner, such as with any suitable adhesive or mechanical fastener, or may be formed integral with the housing 12.
With reference to prior art FIG. 2, an inclined cut-off 50 can be included in place of the straight cut-off 30. The inclined cut-off 50 includes a first chamber 52 and a second chamber 54 adjacent thereto. The first chamber 52 includes a first upstream surface 60 facing the blower wheel 14, and a first downstream surface 62, which is opposite to the first upstream surface 60. Between the first upstream surface 60 and the first downstream surface 62 is a first inclined upper edge 64. The second chamber 54 is smaller than the first chamber 52, and includes a second upstream surface 70 and a second downstream surface 72. The second upstream surface 70 faces the blower wheel 14, and the second downstream surface 72 is opposite to the second upstream surface 70. Between the second upstream surface 70 and the second downstream surface 72 is a second inclined upper edge 74, which is lower than the first inclined upper edge 64. A bottom surface 76 is opposite to the first and second inclined upper edges 64 and 74.
Although the straight cut-off 30 and the inclined cut-off 50 are suitable for their intended use, they are subject to improvement. For example, the cut-offs 30 and 50 often generate undesirable audible tones and broadband high frequency noise as airflow from the blower wheel 14 flows over the cut-offs 30 and 50. The present teachings provide for improved cut-off resonators that address these issues in the art, as well as numerous others as one skilled in the art will appreciate.